1. Field of the Invention
This invention relates to a character reading apparatus which optically reads characters recorded on a recording medium. In particular, the present invention provides a technique of detecting each character field from a character image which has been read.
2. Description of the Related Art
An example of such a character reading apparatus is shown in U.S. Pat. No. 4,461,027 (Patented Jul. 17, 1984). The character reading apparatus gets a character image by reading the recording medium through an optical scanner. This character image is input into a multi-value pattern memory for character identification after being A/D converted. Also, after the character image has been digitally converted, it is input into a 1-bit pattern memory and the character position of each character is detected by taking projections of the character image in the horizontal and vertical direction.
However, this type of character line and character position detection technique has the following disadvantages. Namely, if the density level of a recorded character is low at certain positions on the character, the image may be lost in the digital conversion stage. Therefore, the character line and character position cannot be detected correctly. Consequently, a complete character image cannot be obtained and, as a result, identification of the character is impossible.
In order to resolve the above-mentioned disadvantages, there exists a technique of extracting a plurality of digitally converted images which have been digitally converted at different levels and detecting the character line and character position in each of the respective digitally converted images. Each line and position of the image at each level is detected, and an image comprising the levels best detected is identified. However, the amount of circuitry necessary to perform this technique is extremely large.